I hate to say it because I'm no expert, but the rooster in the back in the first picture looks exactly like my dark brahma. I keep cochins, but when I was new to chickens I purchased a silver laced cochin rooster which turned out to actually be a dark brahma rooster and he looks exactly like yours. What kind of comb does he have? Other than just the similar coloring, brahma have feather on the outsides of their legs and sparce feathers on their feet, like the one in your picture. I linked a picture of what dark brahmas look like from google.
http://www.google.com/imgres?um=1&h...w=155&start=0&ndsp=21&ved=1t:429,r:0,s:0,i:71
Either way, he doesn't really look mottled, or silver laced. If it's cochin, maybe Birchen? You should look at the comb, a brahma has a pea comb while a cochin has a single comb. I'm not kidding when I say he looks exactly like my dark brahma.